Sesimbra (Portuguese pronunciation: [sɨˈzĩbɾɐ]) is a municipality of Portugal, in the Setúbal District, lying at the foothills of the Serra da Arrábida, a mountain range between Setúbal and Sesimbra. Due to its particular position at the Setúbal Bay, near the mouth of the Sado River and its natural harbour, it’s an important fishing town. The population in 2011 was 49,500, in an area of 195.47 km². The present Mayor is Augusto Pólvora.
Besides professional fishing and sport fishing (mainly of swordfish), the most significant revenues in Sesimbra come from tourism. The town is famous for its beaches, fish restaurants and nightlife.
The original name of Celtic origin was Cempsibriga, meaning the Burg (Briga) of the Celtic tribe the Sesim.
Close by, on a mountaintop, 240 m (787.40 ft) above sea level, lies strategically (the ruins of) the Moorish castle. It was taken from the Moors, during the Portuguese Reconquista in the year 1165 by king Afonso Henriques with the help of Frank Crusaders. The battlements afford a beautiful panorama over Sesimbra, its harbour and the surrounding countryside.